In withdrawing from the Paris Agreement on climate change, the United States will leave the ranks of more than 190 nations committed to the international deal and join Syria and Nicaragua as the only other countries that are not participating.

According to the announcement by President Trump Thursday afternoon, the U.S. will become the third country in the world to reject the pact, which is intended to slow the rate of global warming by reducing carbon dioxide emissions.

Syria, in the midst of a civil war, wasn’t expected to sign the agreement and had no involvement with the 2015 negotiations.

Nicaragua denounced the global pact during the 2015 talks, citing concerns over the voluntary nature of the agreement and the lack of punitive measures in place for countries that violate the deal. The nation also balked at the agreement’s aim to limit the global temperature to 2°C, calling for a more ambitious target.

But the carbon emissions of both Syria and Nicaragua are far less than that of the United States, which means that America’s withdrawal could have far greater consequences.

Syria and Nicaragua produced about 70,000 and 16,000 kilotons of carbon emissions, respectively, in 2012, according to World Bank data. The U.S., however, emitted about 6.3 million kilotons — more than 67 times the total emissions of Syria and Nicaragua combined.

Though a U.S. withdrawal wouldn’t take effect until 2020, the shift would send a strong message about the nation’s prioritization of climate change.

Trump had decried the 2015 agreement during his presidential campaign, vowing to withdraw from the agreement within his first 100 days. He claimed that the U.S. economy would save trillions of dollars by abandoning the agreement. In the past he has called the very idea of human-caused climate change a “hoax.”

Some of Trump’s own advisers and Cabinet members, as well as American business leaders and world leaders including Pope Francis, had asked Trump to keep the U.S. in the agreement.